JP5331564B2 - Aircraft tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to an aircraft radial tire used in an aircraft such as a jet passenger aircraft.

  Radial tires are also used on aircraft such as jet passenger aircraft. Since radial tires for aircraft are used at a high internal pressure, the pressure on the contact surface is high. Accordingly, when taking off and landing at high speed or traveling in an airport, the tread portion may be damaged when a step or the like falling on the road surface is stepped on. In particular, when this trauma is large, even the belt disposed on the inner side in the tire radial direction of the tread portion is damaged, and thus rehabilitation by reattaching the tread portion may be difficult. Therefore, in order to prevent such belt damage, a structure in which a belt protective layer for protecting the belt is provided between the tread portion and the belt has been conventionally employed.

  Patent Document 1 discloses an aircraft radial tire having the belt protective layer (in Patent Document 1, a wavy cord protective layer). FIG. 3 is a view showing a belt protective layer provided in such a conventional aircraft radial tire. The belt protective layer 100 is made of a ply in which a plurality of corrugated cords 101 are covered with a coating rubber 102. The belt protective layer 100 has a structure in which both end portions in the longitudinal direction LD are abutted and connected so that the cross-sectional positions of the embedded cords 101 coincide with each other. As a result, the bonding strength between the coating rubbers 102a and 102b facing each other at the butted portion is increased to prevent peeling at the connecting portion.

JP-A-5-294107

  As described above, Patent Document 1 proposes a preferable aircraft tire technology that improves the durability of the belt protective layer by enhancing the bonding of the coating rubber. However, the technique disclosed here is based on the premise that an annular belt protective layer is formed by abutting the start and end of one ply. In such a structure, there is always a portion for connecting both ends to each other (that is, a joint portion). Therefore, it cannot be denied that the strength is inferior to that of an integral type or endless structure having no joint portion. Since aircraft tires are used under heavy loads and high speeds, there is a strong demand for a structure that improves both cut resistance and high speed durability.

In view of the above situation, the present invention is to further improve the structure of the belt protective layer to improve cut resistance and high-speed durability, and to provide an aircraft tire.

The above object is an aircraft tire in which a belt, a belt protective layer, and a tread are sequentially arranged on the radially outer side of a carcass straddling a toroidal shape between a pair of bead portions,
The belt protective layer is formed by applying a strip material in which one or a plurality of corrugated aramid fiber cords are covered with rubber, obliquely with respect to the equatorial plane of the tire from one side edge to the other side of the belt protective layer forming region. In addition, this can be achieved by an aircraft tire characterized by being continuously extended in a zigzag shape substantially in the circumferential direction of the tread through bending at a side edge.

  The cord waveform of the aramid fiber cord is preferably 7.0 mm ≦ A ≦ 9.0 mm and 20.0 mm ≦ W ≦ 40.0 mm, where A is the amplitude and W is the wavelength.

The aircraft tire according to the present invention includes a strip material in which aramid fiber cords are covered with rubber and formed into a thin belt shape, and one side edge of the belt protective layer forming region is inclined with respect to the equator plane of the tire and the side edge. The belt protective layer is formed by extending continuously in a zigzag shape substantially in the circumferential direction of the tread through the bending at. In such a belt protective layer, the strip material is uniformly wound around the entire tire width direction to form an endless belt protective layer. Depending on the number of windings, a desired plurality of layers can be formed in the tire radial direction. Therefore, it is possible to provide an aircraft tire with improved cut resistance and high-speed durability.
In particular, even when the belt protective layer is formed through the above-described bending, since the corrugation is applied to the cord, the cord does not receive a large compressive strain at the bent portion. As a result, the durability of the belt protective layer can be further improved, and a more reliable aircraft tire can be provided.

1 is a cross-sectional view in the width direction of a radial tire for aircraft according to the present invention. (A) is the figure which expanded and showed a part of strip material which comprises the belt protective layer, (b), while the strip material made the whole zigzag without wrinkles within the belt protective layer area width | variety. It is the figure which showed the mode when it winds continuously in the circumferential direction. It is the figure shown about the belt protective layer provided in the conventional radial tire for aircraft.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view in the width direction of a pneumatic radial tire TR for aircraft according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a pair of sidewall portions extending inward in the radial direction RD continuously to the side portion of the tread portion 1, and 3 is an inner peripheral side of each sidewall portion 2. The bead part provided continuously is shown.

  Further, between the bead portions 3, a carcass 4 is provided which includes at least one radial arrangement code ply provided to extend in a toroidal shape, four in the illustrated example, and one outer. The carcass 4 serving as a skeleton of the tire straddling each of the above-described parts 1, 2, and 3 is disposed around the annular bead core 5 in which each side part is embedded in the bead part 3 and wound back from the inside of the tire to the outside. ing. On the outer periphery of the crown portion 7 of the carcass 4, at least one layer, in the illustrated example, four layers of the belt 6, the belt protective layer 8, and the tread portion 1 are positioned in this order. EL is the tire equator plane of the radial tire TR.

In the aircraft radial tire TR shown in FIG. 1, a novel structure is particularly incorporated in the belt protective layer 8 disposed outside the belt 6. Further, this point will be described in detail with reference to FIG.
FIG. 2A is an enlarged view of a part of the strip-shaped strip material 10 constituting the belt protective layer 8, and FIG. 2B is a diagram showing such a strip material 10 in the belt protective layer region. It is the figure which showed typically a mode when it winds continuously in the circumferential direction, making it the whole zigzag shape uniformly within the width 8W. The strip material 10 is continuously zigzag in the circumferential direction of the tread substantially obliquely with respect to the equatorial plane EL of the tire from one side edge to the other side edge of the belt protective layer forming region and being bent at the side edge. The belt protective layer 8 is finally formed by winding. The strip material 10 can be formed into an arbitrary multilayer by stacking in the tire radial direction by setting an appropriate number of windings. When the strip material 10 is wound in a zigzag shape, a laminated portion can be formed by providing an overlapping portion. If the overlap margin is adjusted, a belt protective layer having three or more layers can be formed uniformly.

The strip material 10 shown in FIG. 2 (a) has a strip shape (ribbon shape) in which a cord (in the example, two are shown) in which high-elasticity polyamide is formed in a wave shape is covered with a coating rubber 12. ). More specifically, an aromatic aramid fiber is adopted as a polyamide cord as a cord provided in the strip material 10.
FIG. 2A shows a state of the folded portion TE where the strip material 10 is bent at the right end RE of the belt protective layer region and turned back counterclockwise.

  By the way, aramid fiber is extremely durable compared to general organic fiber and has extremely strong durability against tensile force, but relatively inferior to compressive force. It has been known. Therefore, when a large compressive strain acts on the cord formed of the aramid fiber, that is, when it is used at a bent portion as shown in FIG.

  However, in the case of the strip material 10 shown in FIG. 2A, the cord made of aramid fibers is corrugated, and more preferably, a plurality of cords are embedded in the coating rubber 12 at intervals and integrated as the strip material 10. ing. With such a strip material 10, when the strip material 10 is bent at the turn-up portion TE, the inner aramid fiber cord is wavy (corrugated), so that it is deformed without being bent, and as a result, generation of a large compression strain can be avoided. Therefore, the occurrence of failure can be prevented.

  As shown in FIG. 2 (b), both ends of the region width 8W for using the strip material 10 as the belt protective layer 8 are the folded portions TE, and are bent in a zigzag shape in the tire circumferential direction CD. It is wound. An endless structure can be formed by continuously winding the strip material 10 in the circumferential direction while forming a uniform zigzag shape within the region width 8W. Depending on the number of windings, a plurality of layers can be formed in the tire radial direction.

In addition, the waveform of the aramid fiber cord embedded in the coating rubber 12 as described above, when the amplitude is A and the wavelength is W,
It is preferable that 7.0 mm ≦ A ≦ 9.0 mm and 20.0 mm ≦ W ≦ 40.0 mm.
When the amplitude A is less than 7.0 mm, it becomes close to a straight line, and compression distortion at the time of bending is likely to occur, and inconvenience that durability against FOD (damage caused by foreign matter on the road surface) is poor is likely to occur. . On the other hand, if it exceeds 9.0 mm, the bending of the strip material is large, and the disadvantage that the compressive strain increases is likely to occur. Therefore, the amplitude A is preferably set to 7.0 mm ≦ A ≦ 9.0 mm as described above.

  Further, when the wavelength W is less than 20.0 mm, the inconvenience that the bending is large in the strip material, the number of times of bending is extremely increased, and the durability is inferior easily occurs. On the other hand, if it exceeds 40.0 mm, the inconvenience that durability is inferior with respect to FOD (damage caused by foreign matter on the road surface) tends to occur. Therefore, the wavelength W is preferably 20.0 mm ≦ W ≦ 40.0 mm as described above.

The above-described pneumatic radial tire for aircraft according to the present invention can be manufactured by adding a simple change to the conventional radial tire manufacturing process including two stages of first (1ST) and second (2ND). That is, in the molding process of the unvulcanized tire included in the 2ND process, the belt ply is first wound around the crown portion of the carcass ply of the unvulcanized case. Subsequently, a strip material in which a plurality of aramid fiber cords are coated with unvulcanized rubber on this belt ply is slanted with respect to the periphery of the unvulcanized case from one side edge to the other side of the belt protective layer forming region. And it winds under the arrangement | positioning extended continuously in zigzag shape through the bending in a side edge, and shape | molds an unvulcanized tire. The unvulcanized tire may be vulcanized to produce a tire.

In the aircraft radial tire TR according to the present invention described above, the belt protective layer 8 is formed by continuously winding the strip material 10 in a zigzag shape, so that the structure is almost endless, so that the cut resistance and A structure with improved high-speed durability can be realized.
Here, the belt protective layer 8 is formed by continuously winding the strip material 10 in which the corrugated aramid fiber cord is coated with the coating rubber in a zigzag manner. Therefore, it is possible to provide an aircraft tire in which the durability of the belt protective layer is further improved while reducing the compressive strain acting on the aramid fiber.

  In addition, the tire according to the present invention can appropriately increase the winding of the strip material 10 as necessary, so that it is possible to easily deal with cut impacts that are difficult to prevent with a single belt protective layer by multilayering. it can. Furthermore, if the strip material 10 is prepared in advance and prepared, it is possible to cope with a variety of tire sizes by changing the sequence.

  By the way, a structure in which the above-described strip material 10 is spirally wound on the belt instead of being wound in a zigzag shape along the circumferential direction on the belt as described above is also conceivable. However, in this case, since the cord shape in the strip material 10 is a waveform, portions where the cord interval is widened at both end portions, that is, portions where no cord is present periodically exist between wave troughs (mountains). Therefore, the cut resistance at the edge of the belt protective layer cannot be guaranteed.

  If the aramid fiber is not wavy like the strip material 10 described above, but is wound in a zigzag shape using a rubber-coated strip material as a straight line, a large compressive strain is generated at the folded portion as described above. Therefore, it is assumed that fatigue resistance is deteriorated, and sufficient high-speed durability cannot be obtained.

(Example)
Hereinafter, the Example at the time of applying this invention to the pneumatic radial tire for aircraft (APR size: 1400 * 530R23) is described.
In addition, the coating rubber was coat | covered for the Example for the aramid fiber cord formed in the wave shape. Aramid fiber cords were waved with an amplitude of 8.0 mm and a wavelength of 26.5 mm, and two of them were embedded in a coating rubber with a gap of 4 mm to prepare a strip-shaped strip material having a width of 13.7 mm and a thickness of 1.45 mm. The strip material was wound around the belt in a zigzag manner to produce a pneumatic radial tire provided with a belt protective layer.
Here, the belt material is continuously wound around the belt in a zigzag shape in the circumferential direction of the tread, and is uniformly wound in the tire width direction so as to form two layers in the tire radial direction, thereby forming a belt protective layer. . Here, the structure of the belt protective layer of such an embodiment is referred to as a “zigzag structure”, and the structure of the belt protective layer formed by abutting the start and end of the conventional ply described above is referred to as a “joint structure”.

  For comparison, a conventional tire was tested for cut resistance and high-speed durability based on a joint structure in which a ply as shown in FIG. As the conventional tire here, a tire in which a wavy aramid fiber cord is embedded inside the ply was used.

Furthermore, in order to confirm the effect of the present invention, three kinds of comparative examples were further tested with respect to the present invention in which a strip material in which corrugated aramid fiber cords were embedded was wound in a zigzag shape. In addition, especially the other conditions which are not demonstrated here shall be the same as that of the tire of an Example.
First, in Comparative Example 1, a strip material in which a linear nylon fiber cord was embedded was wound in a zigzag shape to form a belt protective layer. Four layers in the tire radial direction are thicker than the tires of the examples.
Comparative Example 2 was a modification of a conventional tire, and a belt protective layer was formed by using a linear nylon fiber embedded in a wide band-shaped member.
Furthermore, in Comparative Example 3, a strip material in which straight aramid fibers were embedded was wound in a zigzag shape to form a belt protective layer. Two layers in the tire radial direction were used in the same manner as the example tires.

Table 1 below summarizes the test results for cut resistance and high-speed durability.
In addition, as a test for cut resistance, a sharp cutter having a width of 50 mm, a height of 30 mm, and a blade edge angle of 30 degrees is applied to a tire filled with a specified internal pressure on a flat plate, and the load is gradually applied. Was increased. The load applied when the belt protective layer breaks is indicated by an index with the conventional tire as “100”, and the larger the number, the better the performance.
In addition, high-speed durability was judged by the number of tests until a tire failure occurred when repeated take-off test conditions were performed on the indoor drum tester with the specified internal pressure and specified load. Here again, the conventional tire is indicated by an index of “100”, and the larger the number, the better the performance.

  As can be seen from Table 1 above, it can be confirmed that the tires of the examples are pneumatic tires suitable as radial aircraft tires with improved cut resistance and high-speed durability.

TR Radial tire for aircraft 1 Tread part 2 Side wall part 3 Bead part 4 Carcass 6 Belt 8 Belt protective layer 10 Strip material 11 Cord

Claims (2)

An aircraft tire in which a belt, a belt protective layer, and a tread are sequentially arranged on the outer side in the radial direction of the carcass that forms a toroid shape between a pair of bead portions,
The belt protective layer is formed by applying a strip material in which one or a plurality of corrugated aramid fiber cords are covered with rubber, obliquely with respect to the equatorial plane of the tire from one side edge to the other side of the belt protective layer forming region. Further, an aircraft tire characterized by being continuously extended in a zigzag shape substantially in the circumferential direction of the tread through a bend at the side edge. The waveform of the aramid fiber cord, when the amplitude is A and the wavelength is W,
7.0 mm ≦ A ≦ 9.0 mm and 20.0 mm ≦ W ≦ 40.0 mm
The aircraft tire according to claim 1, wherein

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